Method and apparatus for vascular tissue sealing with active cooling of jaws at the end of the sealing cycle

ABSTRACT

An end effector assembly for use with an electrosurgical instrument is provided. The end effector assembly has a first jaw member and a second jaw member. The second jaw member includes a channel defined therein and coupled to a cooling agent source and at least one venting port defined therein and fluidly coupled to the channel. During active cooling of the second jaw member, the cooling agent source is configured to supply a cooling agent to the channel.

BACKGROUND

1. Technical Field

The present disclosure relates to electrosurgical instruments used foropen and endoscopic surgical procedures for sealing or fusing tissue.More particularly, the present disclosure relates to a bipolar forcepsfor sealing vessels, vascular tissues and soft tissues having anelectrode sealing assembly which is designed to limit and/or reducethermal spread to adjacent tissue structures by rapid cooling.

2. Background of the Related Art

Open or endoscopic electrosurgical forceps utilize both mechanicalclamping action and electrical energy to effect hemostasis. Theelectrode of each opposing jaw member is charged to a different electricpotential such that when the jaw members grasp tissue, electrical energycan be selectively transferred through the tissue. A surgeon cancauterize, coagulate/desiccate and/or simply reduce or slow bleeding, bycontrolling the intensity, frequency and duration of the electrosurgicalenergy applied between the electrodes and through the tissue.

Certain surgical procedures require more than simply cauterizing tissueand rely on the combination of clamping pressure, electrosurgical energyand gap distance to “seal” tissue, vessels and certain vascular bundles.More particularly, vessel sealing or tissue sealing utilizes a uniquecombination of radiofrequency energy, clamping pressure and precisecontrol of gap distance (i.e., distance between opposing jaw memberswhen closed about tissue) to effectively seal or fuse tissue between twoopposing jaw members or sealing plates. Vessel or tissue sealing is morethan “cauterization”, which involves the use of heat to destroy tissue(also called “diathermy” or “electrodiathermy”). Vessel sealing is alsomore than “coagulation”, which is the process of desiccating tissuewherein the tissue cells are ruptured and dried. “Vessel sealing” isdefined as the process of liquefying the collagen, elastin and groundsubstances in the tissue so that the tissue reforms into a fused masswith significantly-reduced demarcation between the opposing tissuestructures.

Using electrosurgical instruments to seal tissue may result in somedegree of so-called “thermal spread” across adjacent tissue structures.“Thermal spread” refers generally to the heat transfer traveling alongthe periphery of the electrically conductive surfaces. This can also betermed “collateral damage” to adjacent tissue. As can be appreciated,reducing the thermal spread during an electrical procedure reduces thelikelihood of unintentional or undesirable collateral damage tosurrounding tissue structures which are adjacent to an intendedtreatment site. Reducing the collateral damage to surrounding tissue ormaintaining the viability of surrounding tissue after the sealingprocess is known to promote tissue healing and decrease overall healingtime by stimulating/improving healing response.

Controlling tissue cooling may also reduce adhesion or buildup of tissueon the electrodes and also assist during the formation of the tissueseal, e.g., cross-linking or other chemical bonding, during thereformation or renaturation of collagen. In existing sealing devicesthis cooling takes place in a natural-passive-way (due to heat exchangewith the environment) after energy application is stopped. The coolingrate in this case is determined by thermal properties of the tissue andthe jaw members and by the arrangement of heat exchange between jaws andthe environment.

SUMMARY

In an embodiment of the present disclosure, an end effector assembly isprovided. The end effector assembly has a first jaw member and a secondjaw member. The second jaw member includes a channel defined therein andfluidly coupled to a cooling agent source and at least one venting portdefined therein and fluidly coupled to the channel. During activecooling of the second jaw member, the cooling agent source is configuredto supply a cooling agent to the channel.

In another embodiment of the present disclosure, an electrosurgicalinstrument for sealing tissue is provided. The electrosurgicalinstrument may include a housing having a cooling agent source and avalve configured to control the supply of cooling agent from the coolingagent source. The instrument may also include an end effector assemblyhaving a first jaw member and a second jaw member. The second jaw memberincludes a channel defined therein and fluidly coupled to a coolingagent source and at least one venting port defined therein and fluidlycoupled to the channel. During active cooling of the second jaw member,the cooling agent source is configured to supply a cooling agent to thechannel.

The second jaw member may include a temperature sensor configured todetect a temperature of the second jaw member. The detected temperaturemay be used to determine a duration of time that the cooling agentsource supplies the cooling agent. Alternatively, the cooling agentsource may supply a cooling agent for a predetermined duration of time.The cooling agent may be carbon dioxide or nitrous oxide.

In yet another embodiment of the present disclosure, a method forcooling an end effector assembly having a first jaw member and a secondjaw member having a channel defined therein coupled to a cooling agentsource and at least one venting port defined therein fluidly coupled tothe channel may be provided. The method may include supplying a coolingagent to the channel from the cooling agent source and terminatingsupply of the cooling agent from the cooling agent source. The coolingagent may be vented into the atmosphere via the at least one ventingport.

The cooling agent may be supplied to the channel for a predeterminedduration of time where the predetermined duration of time may bedetermined by measuring a temperature of the second jaw member beforethe supplying the cooling agent to the channel.

In yet another embodiment, the temperature of the second jaw member maybe measured after the cooling agent is supplied to the channel and whenthe second jaw member reaches a desired temperature, the supply of thecooling agent from the cooling agent source is terminated.

BRIEF DESCRIPTION OF THE DRAWINGS

Objects and features of the presently disclosed systems and methods willbecome apparent to those of ordinary skill in the art when descriptionsof various embodiments thereof are read with reference to theaccompanying drawings, of which:

FIG. 1A is a right, perspective view of an endoscopic bipolar forcepshaving a housing, a shaft and a pair of jaw members affixed to a distalend thereof, the jaw members including an electrode assembly disposedtherebetween;

FIG. 1B is a left, perspective view of an open bipolar forceps showing apair of first and second shafts each having a jaw member affixed to adistal end thereof with an electrode assembly disposed therebetween;

FIG. 2 is a schematic view of an endoscopic bipolar forceps according toan embodiment of the present disclosure;

FIG. 3 is an enlarged view of the area of detail of FIG. 2 showing anend effector assembly according to an embodiment of the presentdisclosure; and

FIG. 4 is a chart depicting the temporal dependence of tissuetemperature during a sealing cycle.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure are describedhereinbelow with reference to the accompanying drawings; however, thedisclosed embodiments are merely examples of the disclosure and may beembodied in various forms. Well-known functions or constructions are notdescribed in detail to avoid obscuring the present disclosure inunnecessary detail. Therefore, specific structural and functionaldetails disclosed herein are not to be interpreted as limiting, butmerely as a basis for the claims and as a representative basis forteaching one skilled in the art to variously employ the presentdisclosure in virtually any appropriately detailed structure. Likereference numerals may refer to similar or identical elements throughoutthe description of the figures.

Electromagnetic energy is generally classified by increasing frequencyor decreasing wavelength into radio waves, microwaves, infrared, visiblelight, ultraviolet, X-rays and gamma-rays. As used herein, the term“microwave” generally refers to electromagnetic waves in the frequencyrange of 300 megahertz (MHz) (3×10⁸ cycles/second) to 300 gigahertz(GHz) (3×10¹¹ cycles/second). As used herein, the term “RF” generallyrefers to electromagnetic waves having a lower frequency thanmicrowaves. The terms “tissue” and “vessel” may be used interchangeablysince it is believed that the present disclosure may be employed to sealand cut tissue or seal and cut vessels utilizing the same principlesdescribed herein.

As will be described in more detail below with reference to theaccompanying figures, the present disclosure is directed to the use ofan active cooling system to cool at least one of the jaw members at theend of the sealing cycle. Active cooling of the jaw members may shortenthe sealing cycle, thereby reducing the total operation time.

Referring now to FIGS. 1A and 1B, FIG. 1A depicts a bipolar forceps 10for use in connection with endoscopic surgical procedures and FIG. 1Bdepicts an open forceps 100 contemplated for use in connection withtraditional open surgical procedures. For the purposes herein, either anendoscopic instrument or an open instrument may be utilized with theelectrode assembly described herein. Different electrical and mechanicalconnections and considerations may apply to each particular type ofinstrument; however, the aspects with respect to the electrode assemblyand its operating characteristics remain generally consistent withrespect to both the open or endoscopic designs.

FIG. 1A shows a bipolar forceps 10 for use with various endoscopicsurgical procedures and generally includes a housing 20, a handleassembly 30, a rotating assembly 80, a switch assembly 70 and anelectrode assembly 105 having opposing jaw members 110 and 120 thatmutually cooperate to grasp, seal and divide tubular vessels andvascular tissue. The jaw members 110 and 120 are connected about pivotpin 19, which allows the jaw members 110 and 120 to pivot relative toone another from the first to second positions for treating tissue. Moreparticularly, forceps 10 includes a shaft 12 that has a distal end 16dimensioned to mechanically engage the electrode assembly 105 and aproximal end 14 that mechanically engages the housing 20. The shaft 12may include one or more known mechanically-engaging components that aredesigned to securely receive and engage the electrode assembly 105 suchthat the jaw members 110 and 120 are pivotable relative to one anotherto engage and grasp tissue therebetween.

The proximal end 14 of shaft 12 mechanically engages the rotatingassembly 80 to facilitate rotation of the electrode assembly 105. In thedrawings and in the descriptions that follow, the term “proximal”, as istraditional, will refer to the end of the forceps 10 that is closer tothe user, while the term “distal” will refer to the end that is furtherfrom the user. Details relating to the mechanically cooperatingcomponents of the shaft 12 and the rotating assembly 80 are described incommonly-owned U.S. patent application Ser. No. 10/460,926, now U.S.Pat. No. 7,156,846, entitled “VESSEL SEALER AND DIVIDER FOR USE WITHSMALL TROCARS AND CANNULAS” filed on Jun. 13, 2003.

Handle assembly 30 includes a fixed handle 50 and a movable handle 40.Fixed handle 50 is integrally associated with housing 20 and handle 40is movable relative to fixed handle 50 to actuate the opposing jawmembers 110 and 120 of the electrode assembly 105 as explained in moredetail below. Movable handle 40 and switch assembly 70 are of unitaryconstruction and are operatively connected to the housing 20 and thefixed handle 50 during the assembly process. Housing 20 is constructedfrom two component halves 20 a and 20 b, which are assembled about theproximal end of shaft 12 during assembly. Switch assembly is configuredto selectively provide electrical energy to the electrode assembly 105.

As mentioned above, electrode assembly 105 is attached to the distal end16 of shaft 12 and includes the opposing jaw members 110 and 120.Movable handle 40 of handle assembly 30 imparts movement of the jawmembers 110 and 120 from an open position wherein the jaw members 110and 120 are disposed in spaced relation relative to one another, to aclamping or closed position wherein the jaw members 110 and 120cooperate to grasp tissue therebetween.

Referring now to FIG. 1B, an open forceps 100 includes a pair ofelongated shaft portions 112 a and 112 b each having a proximal end 114a and 114 b, respectively, and a distal end 116 a and 116 b,respectively. The forceps 100 includes jaw members 120 and 110 thatattach to distal ends 116 a and 116 b of shafts 112 a and 112 b,respectively. The jaw members 110 and 120 are connected about pivot pin119, which allows the jaw members 110 and 120 to pivot relative to oneanother from the first to second positions for treating tissue. Theelectrode assembly 105 is connected to opposing jaw members 110 and 120and may include electrical connections through or around the pivot pin119. Examples of various electrical connections to the jaw members areshown in commonly-owned U.S. patent application Ser. Nos. 10/474,170,10/284,562 10/472,295, 10/116,944 and 10/179,863, now U.S. Pat. Nos.7,582,087, 7,267,677, 7,101,372, 7,083,618 and 7,101,371 respectively.

Each shaft 112 a and 112 b includes a handle 117 a and 117 b disposed atthe proximal end 114 a and 114 b thereof that each define a finger hole118 a and 118 b, respectively, therethrough for receiving a finger ofthe user. As can be appreciated, finger holes 118 a and 118 b facilitatemovement of the shafts 112 a and 112 b relative to one another, which,in turn, pivot the jaw members 110 and 120 from the open positionwherein the jaw members 110 and 120 are disposed in spaced relationrelative to one another to the clamping or closed position wherein thejaw members 110 and 120 cooperate to grasp tissue therebetween. Aratchet 130 may be included for selectively locking the jaw members 110and 120 relative to one another at various positions during pivoting.

More particularly, the ratchet 130 includes a first mechanical interface130 a associated with shaft 112 a and a second mating mechanicalinterface associated with shaft 112 b. Each position associated with thecooperating ratchet interfaces 130 a and 130 b holds a specific, i.e.,constant, strain energy in the shaft members 112 a and 112 b, which, inturn, transmits a specific closing force to the jaw members 110 and 120.The ratchet 130 may include graduations or other visual markings thatenable the user to easily and quickly ascertain and control the amountof closure force desired between the jaw members 110 and 120.

As best seen in FIG. 1B, forceps 100 also includes an electricalinterface or plug 200 that connects the forceps 100 to a source ofelectrosurgical energy, e.g., an electrosurgical generator similar togenerator 500 shown in FIG. 1A. Plug 200 includes at least two prongmembers 202 a and 202 b that are dimensioned to mechanically andelectrically connect the forceps 100 to the electrosurgical generator500 (See FIG. 1A). An electrical cable 210 extends from the plug 200 andsecurely connects the cable 210 to the forceps 100. Cable 210 isinternally divided within the shaft 112 b to transmit electrosurgicalenergy through various electrical feed paths to the electrode assembly105.

One of the shafts, e.g. 112 b, includes a proximal shaftconnector/flange 140 that is designed to connect the forceps 100 to asource of electrosurgical energy such as an electrosurgical generator500. More particularly, flange 140 mechanically secures electrosurgicalcable 210 to the forceps 100 such that the user may selectively applyelectrosurgical energy as needed.

As will be described in more detail below, bipolar forceps 10 and openforceps 100 actively cool at least one of the jaw members, e.g., jawmember 304, using a gas cooling agent. The gas cooling agent may becarbon dioxide (CO₂) or nitrous oxide (N₂O) which are non-flammable andneutral with regard to surrounding tissue. The cooling agent may bestored in liquid form in a pressurized reservoir which may be anexternal reservoir 205 (FIG. 1B) or an internal reservoir 305 (FIG. 2).The flow of cooling agent may be controlled by a valve 207 (FIG. 1B) orvalve 307 (FIG. 2).

Figs. 2 and 3 show a schematic view of a bipolar forceps shown generallyas forceps 300. Forceps 300 includes a handle 301, a shaft 302, and twojaw members 303 and 304. The handle 301 includes a reservoir 305 definedtherein that houses a liquefied gas cooling agent. The reservoir ishermetically connected to jaw members 303 and 304 by conduit 306. Jawmember 304 has a channel 313, which is coupled, either directly orindirectly, to conduit 306 (FIG. 3). Jaw member 304 also has a pluralityof venting ports 312. End 314 of each venting port 312 is in fluidcommunication with conduit 306 via channel 313. The other end of eachventing port 312 has a nozzle 315. Nozzles 315 are open to thesurrounding atmosphere. In an embodiment of the present disclosure,nozzle 315 may have a substantially conical shape. Alternatively, achannel (not shown) may be provided instead of nozzle 315 that wouldhave a complex shape that allows for gas expansion. Such channel mayvent the cooling agent into the atmosphere or a condensing cavity.

Valve 307 controls the flow of cooling agent from reservoir 305 to jawmember 304. During the sealing cycle, when electrical sealing currentstops, the generator 500 (FIG. 1A) sends a signal and opens valve 307for a period of time. During this time a portion of cooling agenttravels to channel 313 in jaw member 304. As the cooling agent passesthrough nozzle 315 and is vented into the atmosphere, the cooling agentrapidly expands and the cooling agent's temperature drops, therebycooling jaw member 304. Cooling is completed when the supply of coolingagent is terminated by closing valve 307. This process may be automatedby the generator or may be manually actuated by the surgeon.

There are several possible approaches to determine the period of timethat valve 307 remains open. In one embodiment, it depends on howprecisely the final temperature should be controlled in order to providea requisite sealing quality. In particular, valve 307 may be closedafter a certain volume of cooling agent is released from reservoir 305.This can be achieved by opening valve 307 for a predetermined period oftime.

Alternatively, a temperature sensor 320 disposed on jaw member 304 maybe used to determine the duration of the period of time. For instance,temperature sensor 320 may detect the temperature of jaw member 304 and,when the sensor 320 detects a desired temperature, sensor 320 transmitsa signal directly to valve 307 or indirectly to valve 307 via generator500 to close valve 307. In addition, the temperature of jaw member 304may be measured before cooling and according to the measured temperaturethe necessary amount of cooling agent and corresponding time of a valveopen state may be determined by generator 500, which would then controlvalve 307 accordingly.

Although FIG. 3 shows a channel 313, venting ports 312 and temperaturesensor 320 in jaw member 304, they may be disposed in either jaw member303 or 304 or in both jaw members.

FIG. 4 depicts an example graph representing the temperature of a jawmember during a sealing cycle according to an embodiment of the presentdisclosure. When the sealing cycle is activated at time=0 seconds, thetemperature of a jaw member is increased until electrosurgical energy isno longer supplied to the jaw member at point 402 (e.g., time=5seconds). During passive cooling, as represented by line 404, the jawmember cools at a steady rate which is determined by environmentalfactors such as ambient temperature and the material that composes thejaw members. In active cooling, according to the teachings of thepresent disclosure, as shown by line 406, the temperature of the jawmembers cools much faster than in passive cooling as shown by the highinitial slope of line 406.

While several embodiments of the disclosure have been shown in thedrawings and/or discussed herein, it is not intended that the disclosurebe limited thereto, as it is intended that the disclosure be as broad inscope as the art will allow and that the specification be read likewise.Therefore, the above description should not be construed as limiting,but merely as exemplifications of particular embodiments. The claims canencompass embodiments in hardware, software, or a combination thereof.Those skilled in the art will envision other modifications within thescope and spirit of the claims appended hereto.

What is claimed is:
 1. An end effector assembly, comprising: a first jawmember; and a second jaw member including: an inner-facing surface; anouter-facing surface having at least one opening defined therein; achannel defined within the second jaw member and configured to receive acooling agent; and at least one venting port defined within the secondjaw member and configured to provide fluid communication between thechannel and the at least one opening defined in the outer-facingsurface, wherein the at least one venting port is configured to allowthe cooling agent to vent through the at least one opening defined inthe outer-facing surface of the second jaw member.
 2. The end effectorassembly of claim 1, wherein the second jaw member further includes atemperature sensor configured to detect a temperature of the second jawmember.
 3. The end effector assembly of claim 1, wherein the coolingagent is carbon dioxide.
 4. The end effector assembly of claim 1,wherein the cooling agent is nitrous oxide.
 5. The end effector assemblyof claim 1, wherein, in use, the inner-facing surface of the second jawmember is configured to contact targeted tissue.
 6. The end effectorassembly of claim 1, wherein each one of the at least one venting portsis configured to provide fluid communication between the channel and adifferent one of the at least one openings defined in the outer-facingsurface of the second jaw member.
 7. The end effector assembly of claim1, further comprising at least one nozzle associated with the second jawmember, each one of the at least one nozzles disposed in fluidcommunication between a different one of the at least one venting portsand a different one of the at least one openings defined in theouter-facing surface of the second jaw member.
 8. An electrosurgicalinstrument, comprising: a housing having a cooling agent source and avalve configured to control the supply of cooling agent from the coolingagent source; and an end effector assembly including: opposing jawmembers, each jaw member including an inner-facing surface and anouter-facing surface, at least one of the law members moveable relativeto the other jaw member from a first position wherein the inner-facingsurfaces are disposed in spaced relation relative to one another to asecond position closer to one another wherein the inner-facing surfacescooperate to grasp tissue therebetween; at least one jaw memberincluding: a channel defined therein and fluidly coupled to the coolingagent source; at least one venting port defined therein and fluidlycoupled to the channel, the cooling agent source configured to supply acooling agent to the channel; the outer-facing surface of the at leastone jaw member including at least one opening defined therein, whereinthe at least one venting port is configured to allow the cooling agentto vent through the at least one opening to cool the second jaw member.9. The electro surgical instrument of claim 8, wherein the second jawmember further includes a temperature sensor configured to detect atemperature of the second jaw member.
 10. The electrosurgical instrumentof claim 8, wherein the cooling agent is carbon dioxide.
 11. Theelectrosurgical instrument of claim 8, wherein the cooling agent isnitrous oxide.
 12. A method for cooling an end effector assembly havinga first jaw member and a second jaw member, the second jaw member havinga channel defined therein coupled to a cooling agent source and at leastone venting port defined therein, the at least one venting port disposedin fluid communication between the channel and at least one openingdefined in an outer-facing surface of the second jaw member, the methodcomprising: supplying a cooling agent to the channel from the coolingagent source; terminating the supply of the cooling agent from thecooling agent source; and venting the cooling agent into the atmospherethrough the at least one opening defined in the outer-facing surface ofthe second jaw member via the at least one venting port.
 13. The methodof claim 12, wherein the cooling agent is supplied to the channel for apredetermined duration of time.
 14. The method of claim 13, furthercomprising measuring a temperature of the second jaw member before thesupplying the cooling agent to the channel, wherein the measuredtemperature of the second jaw member determines the predeterminedduration of time.
 15. The method of claim 12, further comprisingmeasuring a temperature of the second jaw member after the cooling agentis supplied to the channel, wherein when the second jaw member reaches adesired temperature, supply of the cooling agent from the cooling agentsource is terminated.